The present invention is an anti-rollover system to prevent rollovers of a concrete mixing truck. In particular, the anti-rollover system provides input data representative of operating conditions of the mixing truck and based upon the input data initiates corrective action to prevent the mixing truck from rolling over during turning maneuvers.
Concrete mixing trucks are used to transport concrete to a work site while mixing the cement and aggregate payload. A chute attached below a discharge opening of the drum delivers concrete from the drum to the work site.
Some concrete mixing trucks include a booster axle system attached to the rear of the truck, which distributes the gross vehicle weight of the truck over a longer wheelbase. The booster axle system is an optional feature which is not included on all concrete mixing trucks. The booster axle is comprised of a pair of substantially parallel arms pivotally attached to the frame rails at the rear of the truck. A set of wheels are attached to the extreme end of the arms. A booster axle cylinder is attached between the truck frame and the arms to raise and lower the booster axle by hydraulic pressure. The booster axle is movable between a load position, an unload position and a raised position. In the load position, hydraulic pressure pushes the booster axle downward towards the ground and the booster axle carries a portion of the gross vehicle weight load. In the unload, deactivated position, pressure is reversed within the booster axle cylinder. Although, the axle still rests on the ground, the booster axle neither receives down pressure from the cylinder nor carries a portion of the load. In the raised position, the booster axle is raised off the ground and rests against the drum roller support pedestal, or rear pedestal.
An operating concern with concrete mixing trucks is roll moments that can exist while the truck is turning, which can cause the truck to roll over. As the truck turns, centrifugal force acts on the truck in a direction opposite the direction of the turn. For turns to the right, the risk exists of the centrifugal force causing the truck to tip over to the left. For example, the potential for roll-over conditions exists when the speed of the truck is too high during a right turn, such as may occur when the truck is traveling on a cloverleaf exit ramp to the right. Additional conditions that may contribute to a roll-over condition include the clockwise rotation of the drum (as viewed from the rear of the truck), which causes the concrete load to laterally shift to the left side thereby resulting in a shifting of the truck's center of gravity. This rotation occurs when the truck is at a standstill and when the truck is being driven. While the drum is rotating, the concrete load in the drum shifts upward along the left side of the drum (as viewed from the rear of the truck). Increasing drum rotation speed laterally shifts the load even further along the left side of the drum and shifts the center of gravity to the left of center.
Also, the truck chassis suspension, due to the lateral load shift, will become more heavily laden on the left side of the vehicle, effectively causing the truck chassis to list to the heavy side. When this event occurs, the listing of the vehicle can be magnified by the downward force applied by the hydraulic cylinder to the booster axle system. This downward force can have a levering effect which may further contribute to a rollover of the truck.
Excessive lateral load shifting, as a result of drum rotation, vehicle speed during turning maneuvers, and the high center of gravity inherent in concrete mixing trucks contribute to a roll moment which can cause truck rollovers to the left during a right turn. An anti-rollover system is needed for concrete mixing trucks that detects a potential roll moment and initiates corrective action to prevent the truck from rolling over during a turn.